Magnetic heads for perpendicular magnetic recording have recently been proposed in order to increase the recording density and capacity of a magnetic disk drive or reduce its size. In one such magnetic head, a magnetic recording head comprises a main pole configured to produce a perpendicular magnetic field, trailing shield, and coil. The trailing shield is located opposite the main pole with a write gap therebetween and configured to close a magnetic path that leads to a magnetic disk. The coil serves to establish magnetic flux through the main pole. The coil is wound around a magnetic core that comprises the main pole and trailing shield.
In the magnetic recording head constructed in this manner, an alternating current is passed through the coil, whereupon a magnetic field produced by the coil changes the direction of magnetization in the magnetic core. Thus, recording on the magnetic disk can be performed with the magnetic field from the write gap in an air-bearing surface (ABS) of the magnetic head.
In the case of high-transfer-rate recording, however, the magnetization reversal response in the magnetic core cannot follow the reversal of the magnetic field created by the coil that is rapid.
Therefore, the timing of the next reversal is inevitably reached before the magnetization in the magnetic core is saturated. If the magnetization is not saturated, the strength of the magnetic field from the write gap of the magnetic core is reduced, so that the quality of signals recorded on the magnetic disk is degraded. Thus, it is difficult to improve the linear recording density.